maximum bore possible

[gary]

What is the maximum bore possible on a 4ag block.
heard the 7a block is thicker. the black top 20 blocks thicker also?
I have seen 83 mm headgskts available so I assume it is done.
I have also read storys of 84 and 85mm bores, dont beleive everything on the internet?

plan is to build a 83mm 7ag.
stock piston choice? mazda mx5( miata) or nissan ca18de.
info seems to show same wrist pin size.
anyone know if the wrist pin height to top of piston is the same as 4ag pistons?
any info helps.
thanks
Gary

[negrizio]

Well 82mm is the maximun you can go; I don't recoment going further.

[gaijin_rokurunner]

Negrizio thats wrong...you can go a maximum of 83mm without sleeving the block...my 20v has 83mm without any problems....old school 4.5ag setups were 83mm kits. Proper prepping and cylinder re-enfrocement, boring and honing is needed to successfully make it happen as you only have once chance to bore the block straight before u either have to sleeve it or scrap it. Without block re-enforcement or the proper machine shop to do it right I dont advise over 82.5mm. Havent looked at a 7a block yet but i assume it would need the same treatment as the 4a.

[kaosboss]

The largest people usually go is 83mm

[gary]

are they using mazda miata pistons, or nissan ca18.
I know custom forged stuff is also possible but I was thinking of off the shelf parts.
sorry but i am a typical corolla owner, cheap.
Gary

[gotzoom?]

Actually, none of those are the correct answer. The only way to tell for 100% sure is to have the cylinder wall thickness ultrasonically measured. Only then can you accurately measure the maximum safe bore. 4A blocks were not all cast exactly the same and there are always imperfections in any mass produced engine. Your best bet would be to bring the block to the shop that will do the boring for you and ask them to measure the wall thickness and let them deal with it. Most race shops do this kind of thing regularly, so they will know the process already.

[gaijin_rokurunner]

Actually your wrong the rule of the industry has always been 83mm max without sleeving and that was determined by ultrasonic testing and the industry standard on acceptable minimum cylinder wall thickness..theres no difference in casting that would be so off that would accomendate any bigger bore without effecting anything else...small imperfections are there but nothing that inconsistant...30 years of experimenting and tuning on the 4ag has proven that thus the reason u have never seen 83.5 mm setups and u rarely see 83mm unless the builder knows exactly what they are doing as u only have one shot to do it right or u need sleeves/new block...my setup is 83mm bore and i had to cement my block to give the cylinder walls its strength back that i had cut out

[yoshimitsuspeed]

Talk about confusing thread necromancy.

[jondee86]

Random off-topic post now deleted This post can now return to the vault.

Cheers... jondee86

[ae86_drifter85]

I was wondering the same thing. Or even sleeve i wanna get 82.mm pistion anyone have any recommencations?

Sent from my SM-G900P using Tapatalk

[ae86_drifter85]

Can i fo 82mm w out sleeving? ?

Sent from my SM-G900P using Tapatalk

[yoshimitsuspeed]

Questions without any information or detail will result in answers without any useful information or detail.

Yes I can make recommendations.

[ae86_drifter85]

I have a 4age 16v out of an ae86 and im curious if i need to resleev my cylinder if go w 82 mm pistion?

Sent from my SM-G900P using Tapatalk

[ae86_drifter85]

Questions without any information or detail will result in answers without any useful information or detail.

Yes I can make recommendations.

Yes this is regarding the sleeves i was wondering if i need to sleeve my cylinder. I have a 4age 16v and i wanna get 82 mm cp high compression pistons.

Sent from my SM-G900P using Tapatalk

[yoshimitsuspeed]

And the posts earlier in this thread didn't answer your question?
I have never heard of someone sleeving a 4AGE. Honestly I don't believe it's practical because by the time you get to a bore big enough to need sleeves the material between cylinders would be too thin to take a sleeve.
With that said as was already said above people have run 83mm pistons without sleeves. At that bore it is smart to get the block inspected. Unless you had a defective block 82mm would be perfectly safe as stated above and in hundreds of other threads across the internet.

[ae86_drifter85]

And the posts earlier in this thread didn't answer your question?
I have never heard of someone sleeving a 4AGE. Honestly I don't believe it's practical because by the time you get to a bore big enough to need sleeves the material between cylinders would be too thin to take a sleeve.
With that said as was already said above people have run 83mm pistons without sleeves. At that bore it is smart to get the block inspected. Unless you had a defective block 82mm would be perfectly safe as stated above and in hundreds of other threads across the internet.

Awesome thanks im a go w the 82 mm piston i appreciate the tech advise

Sent from my SM-G900P using Tapatalk

[MisterJerk]

And the posts earlier in this thread didn't answer your question?
I have never heard of someone sleeving a 4AGE. Honestly I don't believe it's practical because by the time you get to a bore big enough to need sleeves the material between cylinders would be too thin to take a sleeve.
With that said as was already said above people have run 83mm pistons without sleeves. At that bore it is smart to get the block inspected. Unless you had a defective block 82mm would be perfectly safe as stated above and in hundreds of other threads across the internet.

Have you seen the angry4ag thread from the old forum?
sleeved not for huge bore, but because the cylinder wall cracked from 30+psi of boost.
http://forums.club4ag.com/zerothread?id=1638&page=1

[yoshimitsuspeed]

And the posts earlier in this thread didn't answer your question?
I have never heard of someone sleeving a 4AGE. Honestly I don't believe it's practical because by the time you get to a bore big enough to need sleeves the material between cylinders would be too thin to take a sleeve.
With that said as was already said above people have run 83mm pistons without sleeves. At that bore it is smart to get the block inspected. Unless you had a defective block 82mm would be perfectly safe as stated above and in hundreds of other threads across the internet.

Have you seen the angry4ag thread from the old forum?
sleeved not for huge bore, but because the cylinder wall cracked from 30+psi of boost.
http://forums.club4ag.com/zerothread?id=1638&page=1

I hadn't seen that and I am pretty sure it's the first sleeved 4A I have ever seen. It's also one of only a couple cracked blocks I have ever seen. People have made more power on unsleeved blocks. Maybe that one had a casting flaw or was just a particularly thin block or something.
It is still only 82mm. Even then the web between cyls is pretty thin. For that reason I still don't think I would want to use sleeves to try to run more than the 83mm bore people do on unsleeved blocks.

[MisterJerk]

did you see the amount of corrosion in the waster jacket and where the crack was.. wanna bet that had something to do with it.

I have actually never seen a cracked cylinder wall in a 4age IRL. they are very stout. IIRC that block ran at those boost levels for over a year.

[ae86_drifter85]

Do you guys recommend gasket to match the borw size. The reason i ask is i have 81.5 mm piston for my 4age 16v and i havnt been able to find 81.5mm gasket to match. Right now i have factory oem gasket. Whats recommended ? Should i just go w MLS since i alrdy have the block apart.

Sent from my SM-G900P using Tapatalk

[yoshimitsuspeed]

Do you guys recommend gasket to match the borw size. The reason i ask is i have 81.5 mm piston for my 4age 16v and i havnt been able to find 81.5mm gasket to match. Right now i have factory oem gasket. Whats recommended ? Should i just go w MLS since i alrdy have the block apart.

Sent from my SM-G900P using Tapatalk

OEM should be 82mm which will be fine with your pistons. Measure it to confirm.
I can get 81.5mm headgasket but I prefer to go about .5mm over to give a little wiggle room for clearances.